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From Hans Jespersen <h...@confluent.io>
Subject Re: Having 4 Node Kafka Cluster
Date Mon, 06 Mar 2017 13:50:23 GMT
What do you mean when you say you have "2 sites not datacenters"? You
should be very careful configuring a stretch cluster across multiple sites.
What is the RTT between the two sites? Why do you think that MIrror Maker
(or Confluent Replicator) would not work between the sites and yet you
think a stretch cluster will work? That seems wrong.

-hans

/**
 * Hans Jespersen, Principal Systems Engineer, Confluent Inc.
 * hans@confluent.io (650)924-2670
 */

On Mon, Mar 6, 2017 at 5:37 AM, Le Cyberian <lecyberian@gmail.com> wrote:

> Hi Guys,
>
> Thank you very much for you reply.
>
> The scenario which i have to implement is that i have 2 sites not
> datacenters so mirror maker would not work here.
>
> There will be 4 nodes in total, like 2 in Site A and 2 in Site B. The idea
> is to have Active-Active setup along with fault tolerance so that if one of
> the site goes on the operations are normal.
>
> In this case if i go ahead with 4 node-cluster of both zookeeper and kafka
> it will give failover tolerance for 1 node only.
>
> What do you suggest to do in this case ? because to divide between 2 sites
> it needs to be even number if that makes sense ? Also if possible some help
> regarding partitions for topic and replication factor.
>
> I already have Kafka running with quiet few topics having replication
> factor 1 along with 1 default partition, is there a way to repartition /
> increase partition of existing topics when i migrate to above setup ? I
> think we can increase replication factor by Kafka rebalance tool.
>
> Thanks alot for your help and time looking into this.
>
> BR,
>
> Le
>
> On Mon, Mar 6, 2017 at 12:20 PM, Hans Jespersen <hans@confluent.io> wrote:
>
> > Jens,
> >
> > I think you are correct that a 4 node zookeeper ensemble can be made to
> > work but it will be slightly less resilient than a 3 node ensemble
> because
> > it can only tolerate 1 failure (same as a 3 node ensemble) and the
> > likelihood of node failures is higher because there is 1 more node that
> > could fail.
> > So it SHOULD be an odd number of zookeeper nodes (not MUST).
> >
> > -hans
> >
> >
> > > On Mar 6, 2017, at 12:20 AM, Jens Rantil <jens.rantil@tink.se> wrote:
> > >
> > > Hi Hans,
> > >
> > >> On Mon, Mar 6, 2017 at 12:10 AM, Hans Jespersen <hans@confluent.io>
> > wrote:
> > >>
> > >> A 4 node zookeeper ensemble will not even work. It MUST be an odd
> number
> > >> of zookeeper nodes to start.
> > >
> > >
> > > Are you sure about that? If Zookeer doesn't run with four nodes, that
> > means
> > > a running ensemble of three can't be live-migrated to other nodes
> > (because
> > > that's done by increasing the ensemble and then reducing it in the case
> > of
> > > 3-node ensembles). IIRC, you can run four Zookeeper nodes, but that
> means
> > > quorum will be three nodes, so there's no added benefit in terms of
> > > availability since you can only loose one node just like with a three
> > node
> > > cluster.
> > >
> > > Cheers,
> > > Jens
> > >
> > >
> > > --
> > > Jens Rantil
> > > Backend engineer
> > > Tink AB
> > >
> > > Email: jens.rantil@tink.se
> > > Phone: +46 708 84 18 32
> > > Web: www.tink.se
> > >
> > > Facebook <https://www.facebook.com/#!/tink.se> Linkedin
> > > <http://www.linkedin.com/company/2735919?trk=vsrp_
> > companies_res_photo&trkInfo=VSRPsearchId%3A1057023381369207406670%
> > 2CVSRPtargetId%3A2735919%2CVSRPcmpt%3Aprimary>
> > > Twitter <https://twitter.com/tink>
> >
>

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